What is trampoline.S for?

[BVK Groups]

Hi,

    Whenever i try to start executing first thread in a new address
space, its pager is receiving pagefault (at 0x0000002b), eventhough
none of the mapped code touches that place.  Why is it?

    I found out that CHACMOS is mapping trampoline.S at that address. 
I What is this trampoline.S is for?  I tried to understand
trampoline.S code, but i couldn't.  I didnt find any FAQ entry
regarding this.  Can anyone please help me here?

NOTE: I am using pistachio-0.4

Thanks,
-bvk